In the manufacture of wristwatches, one assembly step involves attaching the watch band or strap to the so-called watchhead which includes the assembled case or bezel, crystal, movement and caseback as well as other components. As is well known, the case or bezel of a majority of watches in use today includes a pair of spaced lugs on opposite sides between which the band or strap is attached by means of a conventional spring bar connector. As is also well known, the spring bar connector generally includes a cylindrical sheet metal tube in which spring-urged pintles are disposed and adapted to engage in holes provided in the watercase lugs. The construction of a typical spring bar connector is shown in the Pyne et. al. U.S. Pat. No. 4,270,201 issued May 26, 1981.
In assembling a metal watch band to the watchhead, the spring bar connector is first inserted into a tubular endpiece at the end of the band and then the endpiece is positioned between the lugs of the watchcase and the pintles of the spring bar housed in the endpiece are engaged in the lug holes. In the past, prior art workers have experienced difficulty in assembling the band to the watchhead as a result of uncontrolled spring bar connector movement or shifting in the endpiece of the band. This uncontrolled shifting makes manual or automated assembly of the band to the watchhead fraught with difficulty.
Prior art endeavours to minimize movement of the spring bar connector are illustrated in the Beucke U.S. Pat. No. 1,498,070 issued June 17, 1924, and the Jones U.S. Pat. No. 1,713,533 issued May 21, 1929. The Beucke patent discloses a tubular endpiece having parallel, longitudinal slots defining a strip which is bent inwardly into the tube so that the strip frictionally engages a connector pin therein. The Jones patent discloses a tubular endpiece having an inwardly-bent, circumferential tab that, in one embodiment, frictionally grips a connector pin in the endpiece.
Another somewhat similar technique for fixing a connector pin in a tubular element of a watch strap is illustrated in the Hadley U.S. Pat. No. 1,611,863 issued Dec. 21, 1926, which discloses forming a boss on the tubular element extending inwardly into a groove formed in the connector pin.
Endpiece constructions of various types are illustrated in the Speck et.al. U.S. Pat. No. 2,696,689 issued Dec. 14, 1934; the O'Larte et.al. U.S. Pat. No. 2,871,655 issued Feb. 3, 1959, and the Wyler et.al. U.S. Pat. No. 3,039,263 issued June 19, 1962.